[unreadable] Microarrays are finding increasing use by researchers in a variety of fields. While DNA microarrays have found the largest application in research, there is increasing interest in microarrays consisting of antibodies and other proteins. The overall objective of this research is to develop a commercial laboratory instrument for printing microarrays, based on electrospray technology. The proposed instrument will fulfill two needs. First, it will allow researchers to print high-density microarrays of a variety of compounds, with spot sizes on the order of few micrometers. It would be capable of the parallel printing of a large number of compounds, and could be easily reloaded with a different set of solutions. The proposed printer would match the ease of use and convenience of the contact microarrayers currently available to researchers, but be capable of printing arrays of higher density. Second, the proposed printer will also be capable of combinatorial printing of a large number of different monomers, for in situ synthesis of oligomers and polymers. This is a capability not presently available in commercial instrumentation. [unreadable] [unreadable] [unreadable]